1. Field of the Invention
The present invention relates to a pipe joint adapted to be utilized in flow lines or well casings in which clockwise and counter-clockwise rotation is imparted to the pipe joint in order to provide for the remote subsea make and break connection between a floating vessel and a subsea well or subsea production riser base. More particularly, the invention resides in a pipe joint incorporating a locking connection enabling the pipe joint between the floating vessel and the remote subsea make and break connection to be able to transmit torque, without in any manner affecting the mechanical and pressure integrity of the pipe joint.
Basically, pipe joints of this particular type which are utilized in flow lines or well casings, are pipe joints subjected to reverse rotation in remote subsea make and break connections between a floating vessel and a subsea well or subsea production riser base, and wherein each pipe joint essentially consists of a tubular pin which is adapted to be threaded into the tubular box of a contiguous flowline section or well casing through the intermediary of a sealing screw thread; in essence the tubular pin end having the male threaded end portion adapted to be sealingly screwed into engagement with a female thread formed in the tubular box end. This type of sealing screw thread connection is in common and widespread use in oil field casing and tubing joints and provides the required mechanical interconnection and pressure integrity of the pipe joint. Subsequent to the forming of the pipe joint connection through imparting the necessary locking torque to the mating screw threads between The tubular joint pin and tubular box of the pipe joint, due to the continual clockwise and counter-clockwise rotation which is imparted to the flowlines or well casings, and as a result to the pipe joints, the pipe joints must be able to transmit torque without causing any mechanical loosening of the threaded interconnection between the tubular pin and box of the pipe joint tending to adversely affect the integrity of the joint. In order to maintain this integrity of the pipe joint, from both mechanical and pressure standpoints, consideration has been given in the technology to the incorporation of a locking arrangement or device into the pipe joint which is capable of transmitting the torque generated during the reverse rotation of the flow lines or well casings, and as a result of the pipe joints, without affecting the integrity of the screw threaded interconnections between the components of the pipe joints. In essence, the locking arrangement or device incorporated in the pipe joint will then be capable of transmitting torques produced during the operation of the facilities employing the pipe joints.
Although various types of locking devices are known in the technology which will enable pipe joints or tool joints, such as those which are used in the flowlines or well casings for oil well exploration and production, in general such locking devices are of the type which, although capable of transmitting torque and to some extent protective of the mechanical and pressure integrity of the pipe joints, will weaken the physical structure of the pipe joints so as to reduce the mechanical strength thereof, particularly when employed for lengthy periods and when the pipe joints are exposed to the repeated clockwise and counterclockwise rotation of the flow lines or well casings during operation.
2. Discussion of the Prior Art
Wilkinson U.S. Pat. No. 1,936,815 discloses a tubular condenser wherein an interconnection is provided between the tubular components through the utilization of a locking nut which is threaded onto one connecting tube components and which incorporates a ferrule having a generally wedge-shaped cross-section which is adapted to be wedged into gripping engagement against the outer circumferential surface of the mating tubular component so as to thereby form a locking joint connection. In this instance, the locking element, although capable of transmitting torque, is not adapted to preserve the mechanical and pressure integrity of the condenser joint responsive to the loosening of the locking arrangement.
Hammer et al. U.S. Pat. No. 3,848,905 discloses a high-pressure fitting wherein a ferrule setting nut is adapted to wedge a ferrule into gripping contact against the outer circumferential surface of a first tubular member as the ferrule nut is threaded onto the end of a second connecting tubular member. Although this ferrule construction will provide a pressure-tight connection, the locking device set forth herein is not capable of preserving the mechanical and pressure integrity of a pipe joint, particularly when the latter is subjected to any reversible rotation of the tubular members.
Similarly, Woodling U.S. Pat. No. 2,517,617, Bryson U.S. Pat. No. 4,082,326, Norton U.S. Pat. No. 2,247,032 and O'Sicky U.S. Pat. No. 3,888,521 each disclose pipe joints or tube connectors wherein a ferrule or similar wedge-like element is adapted to be forced into gripping contact against the outer surface of a tubular member through the action of a ferrule setting nut which threadingly engages a second tubular member in order to provide a pressure-tight joint or connection for the tubing. However, none of these prior art locking arrangements are adapted to be able to transmit torque for reversably rotatable piping structures, particularly when such is employed for flowlines or well casings in oil well exploration or production, and would not be capable of preserving the mechanical and pressure integrity of such types of pipe or conduit joints.
Other prior art patents which relate to tool or pipe joints, particularly such as are employed as components of flowlines or well casings in oil well exploration and production, include different types of locking devices for permitting transmission of torque through the pipe joints.
Thus, Holland U.S. Pat. No 1,559,874 relates to a tool joint in which a tubular box adapted for connection to a tubular pipe section is threadingly engaged with a joint pin end through the intermediary of a tapered threaded portion, all of the elements being constructed of hardened steel. In essence, both the pin member and the box member of the pipe joint are arranged to be employed for rotary drilling of oil wells whereby, in order to preserve the integrity of the joint, a suitable locking pin or dowel extends coaxially with the pipe joint so as to interengage the interconnected joint members, with the pin being adapted to be slid out of engagement when necessary to facilitate the assembly and disassembly of the box and pin elements of the pipe joint. Although the structure thereof ensures that the pipe joint can be subjected to torque loads during the rotation of the pipe length, the drilling of apertures or bores into the joint for receiving of the pins or dowels within the members results in a rather weak mechanical construction which can readily lead to the shearing of the dowel or pin and lead to loss in the integrity of the pipe joint during extensive reversing rotation to which such a flowline or well casing may be subjected.
Shamberger U.S. Pat. No. 1,390,931 provides for a stem and bit locking device which may be employed in pipe strings for wells wherein a dowel pin extends between the coupling components, is spring-loaded into positive engagement therebetween and adapted to be recessed when necessary so as to effectuate for disengagement of the coupling elements. Herein, as in Holland '874 the mechanical strength of such an arrangement is quite restricted and, during continuously reversing or alternating clockwise and counter-clockwise rotation, it is difficult to ascertain that the coupling as constructed in this instance would be capable of withstanding high torque loads.
Reynolds et al. U.S. Pat. Nos. 1,407,335 and 1,417,411 each disclose a tool joint in which a pipe joint for oil well drilling consist of a box member and a pin, interconnectable through a tapered locking or sealing thread, is adapted to be secured through the interposition of a dowel pin extending coaxially through the end of the box member and projecting into a recess formed in the pin end. In order to disassemble the locking device, this would entail destroying the integrity of the pipe coupling and, moreover, the structure requires bores to be drilled axially and transversely through the pipe coupling so as to render it mechanically weak when subjected to high torque loads produced during the continuously reversing rotation of the drill string of which such a pipe joint or coupling is a component.
Gill et al. U.S. Pat. No. 2,948,553, Perry U.S. Pat. No. 1,652,542 and Cerbin U.S. Pat. No. 3,382,892 each disclose quick-disconnect valve and pipe couplings wherein axially extending dowel pins may be positioned intermediate the members to provide for torque transmission during the assembly of the coupling and during continual reverse rotation. There is no disclosure of a lock device and construction analogous to that provided for by the present invention.
Finally, Andrews U.S. Pat. No. 1,512,570 discloses the positioning of a locking dowel or bolt intermediate two concentrically arranged members in order to prevent relative rotation therebetween, and has no bearing on a pipe joint locking device for preserving the mechanical and pressure integrity of the pipe joint which is subjected to torque during rotation thereof.
In order to meet the rigorous demands of the technology relative to the construction of pipe joints employed in flowlines or well casings in which there is encountered a reversible rotation, and for the formation of a remote subsea make and break connection between a floating vessel and a subsea well or subsea production riser base, it is necessary to provide a construction for the pipe joints in the flowlines or casings which is able to transmit torque produced during the clockwise and counterclockwise rotation thereof without affecting the mechanical and pressure integrity of the pipe joints.